The well-known Internet Protocol (IP) is a so-called internetwork layer protocol that runs over Ethernet type networks that conform with the well-known IEEE 802.3 standard. That is, Ethernet operates in a broadcasting domain (connectionless mode) in which messages are transmitted over a bus common to a plurality of host modules, i.e., a single cable connected to each of the hosts. Each host monitors the common bus and accepts only those messages bearing its respective address. An illustrative example of such technology as a distribution system (network), shown in the context of a so-called wireless LAN (local area network), is illustrated in FIG. 1. Distribution system 10, which may be an Ethernet type cable, connects directly to a plurality of so-called Access Points (also referred to herein as Access Processors), or hosts, 11-1 through 11-N. Each of the Access Points/Processors (APs) 11 communicates via wireless media with the mobile stations, m.sub.i, (e.g., data terminals, such as portable computers, adapted for wireless communication) that are within its respective coverage area 12-i and accepts messages that are transmitted by those mobiles only. Thus, a mobile station, e.g., m.sub.i, may send a message to a destination, e.g., mobile station m.sub.p, by transmitting the message over the air. One or more APs may receive the transmitted message, but only the AP serving the transmitting mobile, e.g., AP 11-1, accepts the transmitted message, and does so only if the originator identified in the messages is a mobile that is currently being served by AP 11-1. The receiving AP 11, in turn, forwards the message over distribution system 10, which is monitored by all of the APs 11. The AP 11 serving the mobile identified as the destination in the message accepts the message from distribution system 10. The identified AP 11 then retransmits the message over the air to the destination mobile, e.g., mobile m.sub.p.
The delivery of a message within the system of FIG. 1 is predicated on the system "knowing" which AP.sub.i is serving a particular mobile m.sub.i. The system obtains this information through a procedure known as "association", which results in generating a mapping between a particular mobile m.sub.i and a serving Access Processor, AP.sub.i. Once the association between a mobile and Access Processor is established, then the mobile may use distribution system 10 to communicate (via its associated AP) with another mobile.
A mobile, e.g., m.sub.i, initiates the association process when it is "turned on" and begins to scan for a beacon signal that is periodically transmitted by each AP.sub.i. The beacon signal is a so-called management frame which, inter alia, identifies the AP.sub.i, its capabilities, time stamp, etc. The mobile m.sub.i locks onto the strongest of the beacon signals that it receives and transmits a management frame identifying, inter alia, (a) the frame as an association message, (b) a so-called MAC address associated with the mobile m.sub.i and (c) the address of the AP.sub.i. The AP.sub.i, in turn, associates itself with that mobile. At that point, mobile m.sub.1, e.g., m.sub.1, may begin to communicate (via AP.sub.i, e.g., AP 11-1) with another mobile or a terminal connected to distribution system 10.
It is likely that during such communication, one mobile may migrate to a coverage area served by another AP. For example, if mobile m.sub.1 that is communicating with mobile m.sub.p leaves coverage area 11-1 and enters coverage area 11-2, then mobile m.sub.1 has to establish an association with AP 11-2 to continue its communications with mobile m.sub.p. Mobile m.sub.1 does this in response to receiving the beacon management frame transmitted by AP 11-2. In response to that beacon signal, mobile m.sub.1 transmits a reassociation management frame identifying, inter alia, itself, the AP that it is currently associated with (AP 11-1) and the AP that it desires to reassociate with, namely AP 11-2. The latter AP, in turn, confirms the reassociation and notifies AP 11-1 via distribution system 10 that mobile m.sub.1 is now associated with AP 11-2. At that point, the communications between mobiles m.sub.1 and m.sub.p may continue.
(Illustrative association and reassociation procedures as well other "handshaking" procedures/protocols that may be used in the system of FIG. 1 are described in the IEEE Draft Standard 802.11 pertaining to wireless LANs available from IEEE Standards Department, 445 Hoes Lane, P.O. Box 1331, Piscataway, N.J., which is herein incorporated in its entirety by reference. See especially sections 5.4.2.2 (association), 5.4.2.3 (reassociation) and 5.4.2.4 (disassociation) found at pages 19 to 20 of the cited Draft standard.)
An Asynchronous Transfer Mode (ATM) type network does not typically conform with the aforementioned 802.11 standard, since it is not a shared network in the sense that an Ethernet network is a shared (broadcast) network. That is, in an ATM network, switches/hosts communicate with one another via virtual connections, and, therefore, except for conventional broadcast messages, a host in an ATM network receives and transports messages via respective virtual connections, rather than a bus common to the host. Thus, if an ATM network were used to implement distribution system 10, then mobile m.sub.1 would be unable to communicate with mobile m.sub.p after mobile m.sub.1 reassociates with AP 11-2. The reason for this is that, as a result of the initial association, a virtual connection would have been established between AP 11-1 and AP 11-N to establish a communication path from mobile m.sub.1 to mobile m.sub.p (see FIG. 1). A virtual connection would also be established in the reverse direction to AP 11-1. Herein lies the nub of the problem. Messages transmitted by mobile m.sub.p to mobile m.sub.1 after the reassociation occurs would still be transported over the reverse virtual connection to AP 11-1, a connection inaccessible to AP 11-2. Thus, the messages would not be delivered to mobile m.sub.1. Moreover, if just prior to the reassociation, AP 11-1 still had a number of messages destined for mobile m.sub.p stored in its queue, then it is likely that AP 11-1 might attempt to deliver the messages via the established virtual connection. If such messages are transported to AP 11-N via the established virtual connection, then it is likely that they would be out of sequence with messages that AP 11-2 transports to AP 11-N on behalf of mobile m.sub.1 for delivery to mobile m.sub.p.